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THE INTERNAL ENVIRONMENT OF THE BODY 



Part III 



Pineal 

 body 



Liver - 



Gall bladder — / 



Right adrenal 



Duodenum 



Pituitary 

 body 



Parathyroids 



Thymus 



Stomach 

 Pancreas 



Left adrenal 

 beneath pancreas 



Ovary 



Testis 



Fig. 15.1. Location of the human endocrine glands. The hypophysis cerebri of 

 this drawing is commonly known as the pituitary gland. The functions of the 

 pineal body, thymus and spleen are incompletely known but may be in some way 

 associated with the endocrines. The total weight of the endocrine glands of the 

 adult human body is about one quarter of a pound. 



Hormones are carried wherever the blood goes but act only when they reach 

 their particular targets. The relationships of endocrine glands are close, com- 

 plex, and often essential to life. When an animal is exposed to cold, nervous 

 stimuli cause one gland (the anterior lobe of the pituitary) to produce a secre- 

 tion (thyrotrophin) that stimulates another gland (the thyroid) to yield its 

 secretion (thyroxin). This in turn stimulates metabolism with accompanying 

 liberation of heat and energy. This complicated process is covered in the com- 

 mon saying, "I got used to the cold." 



One group of endocrine secretions consists of comparatively simple chemi- 



